Pentasonic PROF 80 computer

All material on this page is contributed by Mr. Pascal Holdry, France. Mr. Holdry obtained permission to publish the documentation and firmware for non-commercial purposes.

The Pentasonic PROF 80 was sold in France as bare board. It was a TRS-80 model I clone, with a partial Expansion Interface logic integrated into the main board. The 12kByte Basic is the same as the LNW Basic ROM (which is the TRS-80 Basic, with some instructions replaced by functional equivalent ones).

PentaSonic advertisement Special PROF 80

Its features are:

• 4 MHz CPU clock,
• 64 k RAM (16k shadow RAM for CP/M),
• 12 kByte LNW80 Basic,
• TRS-80 casette interface,
• Centronics printer interface,
• Serial port (RS232 or 20mA switchable),
• AZERTY (French) or QWERTY keyboard,
• Video output (optional UHF modulator),
• Floppy disk interface, supporting 1 to 4 floppy drives,
• Compatible with TRSDOS, LDOS, NEWDOS ansd OS 80.

Main PROF 80 board

PentaSonic PROF 80 main board

Several options were listed:

• Color graphics card based on the EF9366 graphics controller with 48 kByte RAM. Output is via Scart connector (called Peritel in France), two modes;
  • 8 colors, 256 x 512 pixels,
  • black/white, 512 x 512 pixels,
• CP/M adapter card. This card was placed between main board and CPU,
• Double density adapter.

Hificolor graphics board

PROF80 graphics board "Hifi Color"

The EF9365/EF9366 Graphic Display Prcessor on which the HifiColor is based, has the ability to draw straight vector lines on the screen from a specified starting coordinate and horizontal and vertical deltas. There are four patterns for the line. Another capability is printing characters from a fixed set in four modes; normal (horizontal), normal slanted, vertical (upwards), vertical slanted. There is also light pen support.

The Hifi color card is accessed via a Basic extension GBASIC.

Pentasonic GBASIC demo on Hifi Color board

CP/M adapter

The CP/M adapter card contained a 2 kByte ROM with a boot menu. Two option levels are implemented:

• Drive size selection D: 8" or M: 5 1/4",
• Initial memory configuration;
  • B:DOS/Basic (TRS-80 standard),
  • C:CP/M (ROM, video and keyboard exchanged with upper 16 kByte RAM),
  • X:Non standard.

PROF80 CP/M adapter card

Options were selected by single key strokes, similar to the Omikron Mapper. The boot-ROM also contained detailed error messages if booting failed. This board also works in a regular TRS-80, but without the 16 kByte shadow RAM, so 48 kByte RAM.

Bit 0 of several ports is used to switch the memory map:

F8h (248)	0 - Boot	1 - Normal
F9h (249)	0 - BASIC at 0000h-2FFFh	1 - shadow RAM at 0000h-2FFFh
FAh (250)	0 - CP/M mode	1 - TRS-80 mode (DOS)

Most of the switch logic is on the CP/M adapter but some (ROM/shadow RAM) has to be on the main PROF80 board.

Local links:

• Description of GBASIC commands for the Hifi color card.
• Boot CP/M option ROM dump,
• Contents of the HifiColor graphics board PROM 27S19 or TBP18S030,
• 48 kByte CP/M DMK disk image,
• 64 kByte CP/M DMK disk image,
• the 48 kByte CP/M expanded to 59 kByte DMK disk image,
• Image of the Hifi Color diskette with GTEXTE and GBASIC software,
• A Hypercross version with definitions of both single density (SU) and double density (SV) PROF80 CP/M disks DMK disk image,
• Information on the µInflux HRC 80 board, similar to the HiFi color board,
• Scanned documentation
• Article on the MC-Grafik Terminal also based on the EF9366 graphics controller (german).

External links:

• Pascal HOLDRY site This contains a superset of the information presented here, but in French.
• This PROF80 system is different from the German based Conitec PROF80 which is an ECB-bus based Z80 Eurocard system. More info on this system at www.prof80.de.

More documentation in the documentation directory.

Last update: 2014-06-09

email: fjkraan@electrickery.nl